Catharacta skua, C. lonnbergi,C. antarctica and C. maccormicki (Sibley and Monroe 1990, 1993), cross-regional species, are retained as separate species contra Christidis and Boles (1994) and Turbott (1990) who include lonnbergi and antarctica as subspecies of C. skua and AERC TAC (2003) who include C. maccormicki as a subspecies of C. skua.

Justification:
Although this species may have a small range, it is not believed to approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). The population trend appears to be stable, and hence the species does not approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size may be moderately small to large, but it is not believed to approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.

The Great Skua breeds in Iceland, Norway, Svalbard (to Norway), the Faroe Islands (to Denmark), the Scottish islands and a few on mainland Scotland. It is a migratory species, normally wintering off the Atlantic coast of France and the Iberian Peninsulas, but juveniles can reach as far as Cape Verde, the coast of Brazil, areas of the Caribbean and small numbers also winter on the Grand Banks of Newfoundland (Canada) (del Hoyo et al. 1996).

This marine species avoids land during migration and winter, aggregating in winter in areas where it can scavenge from fisheries. It has a hugely varied diet owing to be being a highly opportunistic feeder. Individuals regularly show individual specialisations in diet and feeding with some colony-specific learning. Breeding begins in May, and it is loosely colonial but highly territorial, breeding on islands on flat ground with some vegetation cover, usually avoiding human contact. Most birds breed within 1 km of their birth place (del Hoyo et al. 1996).

Systems:

Terrestrial; Marine

Citation:

BirdLife International 2012. Catharacta skua. The IUCN Red List of Threatened Species. Version 2014.3. <www.iucnredlist.org>. Downloaded on 03 March 2015.